“'There are three kinds of lies,' Mark Twain was fond of saying: 'Lies, damned lies and statistics.' Selectively presented statistics can be used as much to distort or obscure as they can to illuminate and reveal truths. Much like a carefully cropped photo, a select set of numbers presented in isolation can be used to persuade people of their presenter’s viewpoint, even if in context those stats actually tell a very different story.

http://tv.msnbc.com/2013/03/15/the-nypd-and-its-statistics-on-trial/